The present invention relates to a micro cooling element with a mounting surface for a component to be cooled, in particular a semiconductor component which has within it a micro cooling structure which is connected by connection channels to at least one inflow opening and at least one outflow opening by means of which a cooling medium can be supplied to the micro cooling structure or be discharged from the latter. The present invention further relates to a process and an apparatus for producing this type of micro cooling element.
Micro cooling elements of the type specified above are known and described, for example, in EP 1 672 690. The object of the micro cooling element described in this publication is to achieve improved heat discharge in the region of the mounting surfaces for electronic components. For more homogeneous heat distribution one needs to find a possibility for reducing the minimum outer wall thicknesses in the region of the mounting surface of the component to be cooled without making any sacrifices with regard to insurance against leakages. This is made possible by the cooling element being produced by means of selective laser melting, and so having a monolithic structure which has the advantage in relation to the micro cooling elements with a layered structure that by reducing the wall thicknesses, the feared density problems arising from joints between the layers to be welded together are reduced. A further advantage of using selective laser melting for the production of the cooling element according to the prior art is that with this method, complex internal structures, for example in the form of oval channel cross-sections within the cooling element, can be produced.
In order to realise certain properties of the component to be produced a decision must however be made regarding the material powder to be used in consideration of the advantages and disadvantages of the individual materials. In the known prior art the choice is restricted to one specific material or one corresponding material alloy for the production of the overall component. This requires an appraisal of which material property is essential for the application of the component to be produced and with regard to which parameters must be accepted upon the basis of the restrictions of the latter. The choice of just one material therefore basically constitutes a compromise between the requirements which are also substantially different within the component. As an example of this, it is stated that a micro cooling element should have erosion-resistant properties in the region of the flow-through of the cooling medium, but on the other hand extremely high mechanical stability in the region of its outer limit, and good heat conductivity and the best possible adapted expansion coefficient and resistance against electrocorrosion in the region of the mounting surface for the component to be cooled. Since no material or material alloy combines all of these properties, in the prior art, due to the requirements identified by the customer, one must among other things also decide whether the expansion adaptation to the component to be cooled and resistance against electrocorrosion should be pushed to the background in favour of the cooling capability and erosion resistance, or vice versa.